Radio frequency (RF) amplifiers typically use active devices, such as field effect transistors (FET) and bipolar junction transistors (BJT), to perform the amplification of signals. These active devices typically have a gain that decreases monotonically with frequency. For instance, many of these devices have a gain slope of about six (6) decibels (dB) per octave of frequency. Additionally, incorporating such devices into packages may worsen the gain slope. In many applications, without correction, such a gain slope is often undesirable because it may lead to poor signal quality and/or other undesirable characteristics.
Although, in most cases, the gain of an active device used in RF amplifiers decreases with increasing frequency, in some cases, the gain actually increases with increasing frequency over a particular frequency range. Nonetheless, the changes in gain with frequency, whether increasing or decreasing, results in an uneven gain frequency response. As discussed above, this may be undesirable for certain applications. In general, it may be desirable to adjust the inherent or uncompensated gain frequency response of an RF amplifier to a more desirable gain frequency response.